1. Field of Invention
This invention relates to security devices, and specifically to security devices that mislead potential intruders into thinking that there are occupants at home.
2. Description of Prior Art
Home security is an ongoing concern for nearly everybody. As long as there are people who have homes containing possessions, there are others who would, provided the opportunity, break into those homes to steal those possessions. Alarm systems are available that attempt the detection of intruders and, in response, alert the homeowner, a hired security company, or neighbors. However, as long as the intruder believes he has time where he won't be disturbed, he is often able to disable or circumvent the alarm system. In any case, damage can occur before an alarm is sounded.
A better defense against intruders is to deter them from considering entry in the first place. It has been shown that a dog inside the house can be effective in this regard. Not everybody can, nor wants, to own a dog, though. Also, it is often not feasible to leave a dog alone during extended trips. And, finally, an unrestrained, un-reprimanded dog barking inside can often have the opposite effect—reassuring the desirous intruder that no one is indeed at home.
A proven means for deterring potential intruders is to convince them that someone is at home. It is common for homeowners to place timers on lights to give the illusion of occupancy. This is helpful, but too static. U.S. Pat. No. 4,970,489 describes an occupancy simulator that casts shadows on an interior wall which are meant to resemble people walking to and fro within. This patent suffers the failing that the intended simulation of human presence falls woefully short of actual realism. The device described casts shadows that move steadily across the wall with no apparent animation, as though a statue were being dragged back and forth. Additionally, an observer intuitively understands that distinct shadows are cast on a wall by a single, undiffused light source, and that this type of lighting is extremely rare in a modern home, where room lighting is generally provided by recessed ceiling lights, or by lamps or ceiling lights that include shades which specifically diffuse the light in order to eliminate distinct shadows.
U.S. Pat. No. 5,442,524 describes a different approach to the same ends by casting moving shadows across the inside of a shade or curtain. Although the invention attempts to incorporate a certain degree of randomness to the speed of the parade of shadows, the fact that they always move in one direction, and that their shapes remain fixed and inanimate, leave the result to also fall far short of a convincing simulation of human movements. Additionally, although the rate of rotation of the generating mechanism is not constant, the shadow patterns still repeat every few minutes, thus betraying the artificial source.
Although it is common to leave lights and even a radio on inside, there are few better indications of occupancy than the distinctive flickering, subtly changing light from an operating television. Some people do indeed leave a visible television on while out for an evening, but this is rarely considered practical for extended absences. Additionally, the televisions may be located in inner rooms where they would not have visible indications from outside.
U.S. Pat. No. 5,252,947 to Marciano describes a home security device for simulating a television. This method, however, lacks substantial ability to convincingly mimic a modern television for multiple reasons. Firstly, the invention teaches a flasher for varying the brightness of a light source. These known flasher devices enable electricity to flow in an interrupted, semi-regular fashion that, when used with the light source, produce a slow-rhythm strobing effect. Further, the invention describes a twin filament, blue tinted bulb, allowing the output of the invention to assume two different levels of brightness. A plausible resulting output of the security device is presented herein in FIG. 1. The radiated intensity assumes a lower level 2 when only a first, less bright filament is energized, and a second level 4 when a more powerful filament is energized. Typical incandescent bulbs have a response time shown as TR, allowing a short transition time between levels. Marciano asserts that this resulting combination produces a “random and varying brightness”, but known flasher technology can assume only a modest variation of time values. Presumably, the periods of time where the output intensity is low (TL) and high (TH) can be made to vary somewhat, although a method for doing so is not taught. Similarly, the light output of the taught twin-filament bulb can be expected to assume only two discrete values. This is in contrast to the continuous variation of intensity produced by a real television. Additionally, the nature of the light output of the security device is that it shifts alternately from high to low and back again. This would appear quite mechanistic and predictable to an observer. A real television might, over a particular interval of time, shift from low to medium, to high, and then to higher still.
These shortcomings notwithstanding, however, the device of U.S. Pat. No. 5,252,947 thus simulates the light output of a television to a first approximation. The invention may plausibly yield a first impression to a potential burglar of a functional television. The actual light output of a real television, however, is far more subtle and dynamic than could be produced by the teachings. Even if the flasher device was somehow made to switch on and off in a more truly random manner, this still would not fairly simulate an actual television in operation. A typical television image consists of complex patterns, as scenes fade, swell, abruptly change, or slowly transition as the camera pans, resulting in images that thusly fade, swell, flick, and remain nearly steady for varying periods of time. The light output cast upon a window by a real television is highly characteristic; it is not truly random. While a burglar may be momentarily fooled by the invention, further observation would likely cause him to realize that the source of the illumination is something other than a real television. The burglar does not need to understand the details of why the simulation is inaccurate; humans are remarkably good at recognizing even subtle patterns. A poor simulation or obvious ruse can have the undesirable effect of confirming to the would-be burglar that the house is, in fact, unoccupied. Further, the invention teaches a blue light, which is appropriate for a black-and-white television, whereas virtually all modern televisions for home use are color. The light source of the invention is “multi-color”, meaning that the filament is white, but the glass bulb itself is blue. There is no teaching or suggestion that the overall color of the illumination produced by the invention vary in hue to simulate the output of a color television. The color shifts of the light cast by a color television are often subtle, but human beings (including would-be burglars) are remarkably adept at discerning even slight variations in color.
Additionally, the response time of a typical incandescent light is fixed by the thermal time constant of the filament, and is on the order of a tenth of a second. In a real television, some intensity level shifts are often much shorter, being virtually instantaneous. Other level shifts are much longer, being on the order of several seconds. The fixed time constant of U.S. Pat. No. 5,252,947 does not mimic the widely varying rise and fall times of the output of a true television. Further, the invention does not actually teach or suggest a true method of producing a truly random and dynamically varying brightness. What is needed is a more accurate simulation of the light output of a modern color television.
Finally, U.S. Pat. No. 5,252,947 describes an incandescent bulb which is wasteful of energy and could burn out when operated over extended periods of absence.
As is demonstrated in the failings of all of the just-described patents, humans and their activities exhibit both a subtly and a sophistication that is not readily imitated by regular, repetitive actions, whether a flashing light intended to imitate an operating television, or carousel-type shadows moving back and forth across a wall or window covering.
Advantageous would be a device that accurately simulates an operating television that could be easily positioned anywhere in the home.